Control methods of root rot and stem rot of ginkgo biloba seedlings

Ginkgo seedling is the basis of the development of ginkgo planting industry, the key to success lies in the control effect of root rot and stem rot. The two major diseases of ginkgo biloba seedlings are not only highly susceptible, but also difficult to control after infection, often causing a large number of dead seedlings until the whole army is wiped out. The causes of root rot and stem rot of ginkgo biloba seedlings can be divided into two types: infectious and non-infectious. Infectious pathogen means that the disease is caused by pathogenic fungi, while non-infectious pathogen means that the disease is caused by some abiotic factors, mainly excessive or insufficient soil water content, grass damage, drug damage and so on.

The prevention and control of these two kinds of diseases generally adopt seedling-raising technical measures and chemical control technical countermeasures. Among them, the prevention and control of seedling technical measures is a permanent cure, because it can prevent the occurrence of infectious, non-infectious root rot and stem rot. For example, unobstructed drainage and irrigation, no stagnant water in nursery and seedling bed, non-infectious root rot basically does not occur, shading can reduce the infectious stem rot caused by high temperature sunburn to a minimum, not only that, but also greatly reduce the production cost.

Technical measures for raising seedlings

Carefully select the planting and seedling nursery of Ginkgo biloba: the plots with convenient drainage and irrigation, previous rice fields or wasteland with obvious drop should be selected one by one, among which sandy loam or light clayey soil is the best.

Lower foot base fertilizer: base fertilizer directly affects the growth of ginkgo biloba seedlings, and its effect is much more significant than soil topdressing and foliar fertilizer spraying.

Make great efforts to open deep trenches: the rainy season is from June to the middle of July, and ginkgo seedlings avoid water stains, which is one of the main causes of root rot, so great efforts should be made to open deep ditches. It is required that the depth of the nursery ditch in each field is 0.5m and the depth of the middle trench is 0.3 m. In addition, the growth of seedling bed should not exceed 10 m, and the height of seedling bed should be more than 0.3 m. If it does not reach this standard, infectious or non-infectious root rot will inevitably occur in the seedlings.

Plastic film mulching seeds: plastic film mulching seeds make the seedlings unearthed early, the corresponding fast-growing period in advance, and the seedlings are relatively strong and highly lignified, thus enhancing the resistance of seedlings to pathogenic fungi.

Seedling mattress core soil and heart soil cover seed: take the core soil less than 1 m deep on the hillside to pad the seedling bed and cover the seed, which can not only greatly reduce the breeding of weeds in the seedling bed and save a lot of labor, more importantly, there are few substances available for bacteria in the core soil and can effectively inhibit the production of bacteria.

Timely weeding: weeds compete with ginkgo seedlings for water in spring, make the field poor permeability and muggy, and make ginkgo leaves rot by steaming in the climate of long rain. In addition, the pathogens of weed transmission, such as chewable and piercing mouthparts insects hidden in weeds, cause seedling wounds, so that pathogenic fungi can invade and become susceptible to stem rot. Therefore, weeds should be removed as soon as possible after ginkgo seedlings are unearthed, so as to save labor and money for field management in the future, and lay the foundation for preserving and strengthening seedlings.

Treatment of diseased seedlings: at the initial stage of infectious root rot and stem rot of ginkgo biloba seedlings, we should make up our mind to remove the diseased seedlings and destroy them centrally, disinfect the soil at and around the original rhizosphere of the pathogen, and spray pesticides on healthy seedlings.

Shading: ginkgo biloba seedlings are more tolerant to shade, so shading creates good environmental conditions for its growth. After entering the middle of July, it can last high temperature and drought for several months. Shading can greatly reduce the ground surface temperature and prevent the root neck burn of ginkgo biloba seedlings from stem rot or physiological death.

Chemical control countermeasure

Chemical control is a technical measure that must be taken after the occurrence of root rot and stem rot of Ginkgo biloba seedlings. As long as timely and scientific application, the disease can be effectively controlled.

Seed disinfection: ginkgo seed disinfection can not only kill the germs on the surface of the seed nucleus, but also protect the seeds from soil pathogens. The seeds can be soaked in carbendazim 500 times solution for 5 minutes to dry for mixed sand stratification storage.

Ginkgo biloba stem rot control ginkgo biloba (Ginkgo biloba L.) is a deciduous tree of Ginkgo biloba family and Ginkgo biloba. Ginkgo biloba, which appeared hundreds of millions of years ago, is the oldest relict of gymnosperms left over from the Quaternary glacier movement. Ginkgo biloba is rare and scattered in the world, hundreds of years old trees are rare, and all other plants of the same class have become extinct, so ginkgo biloba is also known as a living fossil. Varieties and varieties are: yellow leaf ginkgo, tower ginkgo biloba, split ginkgo biloba, weeping branch ginkgo biloba, ginkgo leaf ginkgo and so on 26 kinds.

Control of stem rot of Ginkgo biloba (1) Distribution and harm of the disease is common in all ginkgo seedling areas. It often occurs in 1 ~ 2-year-old ginkgo seedlings, especially in one-year-old seedlings, which often cause a large number of seedlings to die. (2) at the initial stage of symptom onset, the seedling base turned brown, the leaves lost normal green, and drooped slightly, but did not fall off. The susceptible site rapidly expanded upward, so that the whole plant withered. The basal cortex of the diseased seedling was shrunk, and the intradermal tissue was spongy or powdery, with many small black sclerotia. The pathogen can also invade the xylem of seedlings, so small sclerotia can sometimes be seen in the brown hollow pith. After that, the pathogen gradually spread to the root, causing the root bark cortex to rot. If you pull out the diseased seedlings by hand, you can only pull out the xylem and leave the root cortex in the soil. The stem rot of Ginkgo biloba cuttings can also occur under the condition of high temperature or low temperature, which can make the cuttings epidermis sleeve on the xylem and all the phloem parenchyma blacken and rot. (3) the pathogen of stem rot of Ginkgo biloba is Macrophomiaphas~oli (Maubl) Ashby, which belongs to Chlamydomonidae and Chlamydomonidae. This bacteria likes high temperature and is suitable. The growth temperature is 3032 ℃, but the pH is not strict, so it can grow well between pH4~9. (4) the pathogen of stem rot usually lives saprophytic in soil and belongs to weakly parasitic fungi. Invade from the seedling wound under suitable conditions. Therefore, the occurrence of the disease is related to the host and site environmental conditions. The root cause of seedling damage is due to the high surface temperature, the base of the seedling is burned by high temperature, resulting in the invasion of bacteria. The lower the degree of Lignification of seedlings, the higher the incidence of the disease. When the seedbed was low-lying and stagnant water, the incidence also increased significantly. From June to August, when the high temperature of the seedling bed reached more than 30 ℃, the 10~l5d of ginkgo cuttings began to occur, and when it was serious, the scion blackened and died. The results showed that antagonistic actinomycetes could effectively inhibit the spread of the disease. (5) according to the causes of stem rot of Ginkgo biloba, prevention should be given priority to. a. Sowing early to sow as soon as the soil is thawed, this measure is beneficial to the Lignification of seedlings in the early stage and enhance the resistance to high temperature on the soil surface. b. Reasonable dense sowing is beneficial to give full play to the group effect of seedlings and enhance the resistance to the external adverse environment. The experiment showed that the smaller the seedling density, the higher the incidence, and the higher the density, the lower the incidence. Practice has also proved that in the past, after sowing 25~40kg seeds per mu, such as changing the sowing rate of 80~l00kg seeds per mu, not only the incidence decreased, but also the seedling yield per unit increased, which not only saved the land but also reduced the disease. c. After the seedlings of underground pests are harmed by underground pests, they are easily infected by stem rot pathogens. Therefore, attention must be paid to the elimination of underground pests before and after sowing. d. To prevent mechanical damage of seedlings, annual sowing seedlings or annual transplanting seedlings must be careful not to damage the roots of seedlings in the process of weeding or seedling planting, otherwise it is easy to cause stem rot. e. Shading and cooling in order to prevent the increase of ground temperature caused by solar radiation, measures such as setting up shade shed, covering grass between rows, planting corn, cutting and shading should be taken to reduce the harm to seedlings. f. Irrigation and spraying should be timely in order to reduce the surface temperature in the high temperature season, and spraying should be adopted where there are conditions, which is more conducive to reducing the occurrence of diseases. g. Drugs and biological control combined with irrigation can be sprayed with a variety of fungicides such as topzine, carbendazim, Bordeaux solution and so on. Antagonistic actinomycetes can also be added when topdressing organic fertilizer in the middle of June, or plant ash / superphosphate (1GB 0.25) and antagonistic actinomycetes can be added. Prevention and treatment of stem rot of Ginkgo biloba

The disease is common in all ginkgo seedling areas. It often occurs in 12-year-old ginkgo seedlings, especially in one-year-old seedlings, which often cause a large number of seedlings to die.

2 symptoms: at the initial stage of the disease, the base of the seedlings turned brown, the leaves lost their normal green, and drooped slightly, but did not fall off. The susceptible site rapidly expanded upward, so that the whole plant withered. The basal cortex of the diseased seedling was shrunk, and the intradermal tissue was spongy or powdery, with many small black sclerotia. The pathogen can also invade the xylem of seedlings, so small sclerotia can sometimes be seen in the brown hollow pith. Then the pathogen gradually spread to the root, causing the root bark cortex to rot. If the diseased seedlings are pulled out by hand, they can only be inserted into the xylem, while the root cortex is left in the soil. The stem rot of Ginkgo biloba cuttings can also occur under the condition of high temperature or low temperature, which can make the cuttings epidermis sleeve on the xylem and the phloem thin tissue blacken and rot.

3 pathogens: the pathogens of stem rot of Ginkgo biloba are Chrysospora and Chrysosporaceae. MacrophomiaphaoliMaublAshby, a charcoal rot pathogen of the genus Ginkgo biloba, likes high temperature and is suitable. The growth temperature is 3032 ℃, but the pH is not strict, and the pH49 can grow well.

(4) incidence rule: stem rot pathogen usually lives saprophytic in soil and belongs to weak parasitic fungi. Invade from the seedling wound under suitable conditions. Therefore, the occurrence of the disease is related to the host and site environmental conditions. The root cause of seedling damage is due to the high surface temperature, the base of the seedling is burned by high temperature, resulting in the invasion of bacteria. The lower the Lignification level of seedlings, the higher the incidence of the disease. When the seedbed was low-lying and stagnant water, the incidence rate also increased significantly. For ginkgo cutting seedlings, when the high temperature of the seedling bed reached more than 30 ℃ in June, 10l5d began to occur after cutting, and in severe cases, a large area of scion blackened and died. The results showed that antagonistic actinomycetes could effectively inhibit the spread of the disease.

(5) according to the causes of stem rot of Ginkgo biloba, prevention should be given priority to.

a. Early harvest and sowing as soon as the soil is thawed, this measure is beneficial to the early Lignification of seedlings and enhance the resistance to high temperature on the soil surface.

b. Reasonable dense sowing is beneficial to give full play to the group effect of seedlings and enhance the resistance to the external adverse environment. The experiment showed that the smaller the seedling density, the higher the incidence, and the higher the density, the lower the incidence. Practice has also proved that in the past, after harvesting 2540kg seeds per mu, such as the harvest of 80l00kg seeds per mu, not only the incidence decreased, but also the seedling yield per unit increased, which not only saved the land but also reduced the disease.

c. After the seedlings of underground pests are harmed by underground pests, they are easily infected by stem rot pathogens. Therefore, attention must be paid to the elimination of underground pests before and after harvest.

d. To prevent mechanical damage of seedlings, annual harvested seedlings or annual transplanted seedlings must be careful not to damage the roots of seedlings in the process of weeding or planting, otherwise it is easy to cause stem rot.

e. Shading and cooling in order to prevent the increase of ground temperature caused by solar radiation, measures such as setting up shade shed, covering grass between rows, planting corn, cutting and shading should be taken to reduce the harm to seedlings.

f. Irrigation and spraying should be timely in order to reduce the surface temperature in the high temperature season, and spraying should be adopted where there are conditions, which is more conducive to reducing the occurrence of diseases.

g. Drugs and biological control combined with irrigation can be sprayed with a variety of fungicides such as topzine, carbendazim, Bordeaux solution and so on. Antagonistic actinomycetes or plant ash / superphosphate (10.25) and antagonistic actinomycetes could also be added when applying organic fertilizer in the middle of June.